Info taken from Management of Pest Insects in and Around the Home
Excessive, persistent moisture is the most important condition allowing many types of pest infestations to establish and persist.
Not only is water critical to the health and normal metabolism of all forms of life, its abundance leads to the growth of various molds, fungi, and other microorganisms which are the primary food source for numerous insect species.
Homeowners should limit the occurrence of persistent moisture in and around their home. Moisture problems can only be remedied by correcting the underlying cause(s). Some common sources of excessive, or persistent, moisture that may lead to a pest problem include but are not limited to:
- Leaking faucets or water lines;
- Condensation, for example on pipes, in walls and under insulation;
- Improper ventilation of walls, attics, crawlspaces, or basements;
- Roof leaks, especially those that are the result of improperly installed flashing around pipe penetrations, sky lights, and chimneys (Figure 8A);
- Improper landscape grade resulting in poor surface water drainage patterns;
- Misdirected sprinkler heads;
- Gaps around windows (especially bay windows) and doors that allow water behind the structure’s exterior sheathing (Figure 8B);
- Clogged gutters and downspouts (Figure 8C);
- Downspout and air conditioner drain lines that deposit water within five feet of the structure (Figure 8D).
Property owners should ensure that:
- Rainwater flows away from their home by examining the grade or slope of the landscape to make certain it is appropriate;
- Gutters, downspouts, roof, and air conditioner condensate drainage patterns are operating properly and depositing water away from the foundation;
- Attics, crawlspaces, and basements are properly ventilated;
- A vapor barrier is in place in the crawlspace;
- Sprinklers are positioned properly;
- There is no standing water or persistent wet spots next to the foundation or in the crawlspace.
For more information see Management of Pest Insects in and Around the Home